YUI: 3-way Resizable Panel with iFrame inside

Resizable Panel #1: This technique uses pure CSS to make the iframe invisible when the panel starts resizing.

Resizable Panel #2: This technique uses a mixture of JS and CSS to mask the iframe when the panel starts resizing. I have the mask set with a light opacity so you can see it.

Javascript Source for Panel #1 - Javascript Source for Panel #2 - Css File for both examples

Resizable Panel #1

Resizable Panel #2